USB sound card.

I'm looking for a good USB sound card with 5.1 out. Something like the Creative AUDIGY and has compariable sound quality of my Turtle Beach Santa Cruz (24 bit). The reason I don't want the AUDIGY is because I've heard it eats up resources. How bad is it? I have a PII 600, 192MB that runs extremely smooth. Runs MediaCar with MP3 + GPS + Netstumbler without any hiccups. How hard of a preformace hit will I get?

I read one review that said it was taking up something like 15% of the cpu on a p4 3GHz machine.

I ended up getting the aurillium, even though it was rated lower in just about all the tests (except cpu usage) but it is bus powered, and I didn't want to bother with wumming more power lines. I am having a problem with hard drive noise. It is a lot better than the onboard sound, but it is still noticeabel when noting is playing, and it is kinda annoying. I would like to try out the audigy to see if I have the same problem some day (or maybe I'll just see if I can find a headunit that has a digital input)